Spark timing control

ABSTRACT

A spark timing control for an internal combustion engine. A suction motor is connected to the timing mechanism to produce spark advance when moved in one direction and spark retard when moved in the opposite direction. The motor comprises a housing having a flexible diaphragm dividing the housing into a pair of chambers and is moved by a speed responsive valve connecting the pressure in the intake manifold to one or the other chambers.

[4 51 May 27, 1975 SPARK TIMING CONTROL 9/1966Walker........................... 123/117 A Inventor: Brooks Walker,1280 Columbus San Francisco Calif 94108 Primary Examiner--Charles .l.Myhre June 22, 1971 Assistant ExaminerRonald B. Cox

[22] Filed:

Attorney, Agent, or F irm-Everett G. Clements 21 Appl. No.: 155,651

[57] ABSTRACT A spark timing control for an internal combustion engine.A suction motor is connected to the timing mechanism to produce sparkadvance when moved in [52] US. 123/117 A one direction and spark retardwhen moved in the 0p- [51] Int. F02p 5/04 posite direction. The motorcomprises a housing hav- [58] Field of 123/117 A ing a flexiblediaphragm dividing the housing into a pair of chambers and is moved by aspeed responsive [56] valve connecting the pressure in the intakemanifold to one or the other chambers.

References Cited UNITED STATES PATENTS 2,708,918 5/1955Caddock......................... 123/117 A 7 Claims, 2 Drawing FiguresSPARK TIMING CONTROL This application is a continuation of Ser. No.593,363 filed 1 1/10/66 and now abandoned.

The invention relates to smog control arrangements in internalcombustion engines and more particularly to ignition control deviceswhereby the emission of noxious by-products of combustion is reduced.

Various arrangements are known whereby the ignition spark, which isbasically timed in correlation with the engine speed, and may besubjected to so called governor advances depending upon the variousspeed ranges, is additionally regulated according to the mode ofoperation, e.g. idle cruise, acceleration or deceleration, etc. Sucharrangements usually comprise sensing elements which are operative todelimit periods of manifold suction operated advance, resp. retardmodifications of spark timing. While known arrangements of this type areeffective to accomplish various objectives, this invention is believedto offer an improvement or other advantages over known devices.

It is now proposed according to the invention that improved results maybe achieved with an arrangement including a speed sensing device and asuction motor which together are operative to achieve, among otherobjectives, a suction operated advance when the engine decelerates abovea given index speed, e.g. around 1000 rpm, and a suction operated retardwhen the speed lies below this index with a throttle in idle position.

It is accordingly one object of the invention to provide mechanismswhereby manifold suction may be utilized to provide special regulationof the ignition timing in a novel manner for reduced exhaust emissionsduring certain cycles of operation.

It is another object of. the invention to provide a mechanism which willallow a shift from a suction operated ignition advance device to asuction operated ignition retard device, both of which are effected andcontrolled by engine developed suction, solely for the reason that theengine speed passes through a predetermined engine index speed.

It is a third object of the invention to provide mechanisms wherebyaforesaid shift from suction operated advance to a suction operatedretard by an engine speed sensing device may be accomplished withoutundue interference with other functions of the engine.

It is a fourth object of the invention to provide a mechanism of thekind described which will not be adversely affected in a significantdegree by changes in barometric pressure of altitude changes. (Cf. herethe attached copy of page 6 of the Chrysler Corporation pamphletentitled Cleaner Air package, as revised in January 1966).

It is a fifth object of the invention to provide a mechanism which willimprove the starting characteristics of internal combustion engines incomparison with the operation of engines having a governor operatedspark retard for idling. In applicants device suction operated sparkretard does not occur during the short cranking of a normal start assufficient suction is not developed until the engine starts, whileinsuring that such suction operated retard becomes effective as soon asthe engine is idling at normal warm operation.

It is another object of the invention to provide a mechanism which willprevent the actuation of the suction operated ignition to be retardedwhen the engine speed is abnormally low, while the throttle valve isalmost wide open, which results in little engine developed suction, asis common in vehicles having straight gear (stick shift) transmissionwhile lugging without the benefit of the slip common in automatictransmissions. The lugging characteristics of an engine having agovernor operated retard at idle will be less desirable than luggingwith applicants device.

It is another object of the invention to provide a mechanism which willnot produce a suction operated retard while decelerating above apredetermined speed-- a condition found in engines depending upon a portbelow the low edge of the throttle butterfly to control the suction to asuction operated retard mechanism, as shown in FIG. 2 of applicants U.S.Pat. No. 3,162,184, issued Dec. 22, 1964, and entitled Spark TimingControl," or to a closed-throttle operated valve between the intakemanifold and a suction operated retard device, as shown in FIG. 1 ofapplicants cited U.S. Pat. No. 3,162,184.

It is another object of the invention to provide a mechanism whereby asuction operated advance is activated when the engine is deceleratingabove the predetermined speed--a shortcoming of certain other devices(cf. applicants cited U.S. Pat. No. 3,162,184, or as shown in Glens 1962Auto Repair Manual, page 360, paragraph 4456-8), per copy attached.

It is another object of the invention to provide mechanisms for theattainment of aforesaid objects which may be utilized in connection withany internal combustion engine having an intake manifold and an ignitiontiming device and is adaptable to converting engines to reduced exhaustemissions.

It is another object of the invention to provide mechanisms foraccomplishing the aforesaid results and whereby engine developed suctionis employed solely as the source of motive energy and all discriminatingfunctions are discharged by means independent of engine developedsuction.

These and other objects of the invention and its particular advantageswill become apparent from the following detailed description of itsnovel aspects in the context of a preferred embodiment, as illustratedin the drawings, wherein:

FIG. 1 shows a schematic plan view of one form of the invention,-partlyin section, partly broken away.

FIG. 2 shows a modification of a detail of FIG. 1 in larger scale, alsopartly in section and partly broken away.

For the sake of simplicity, the drawing has been limited to the bareessentials. Conventional routines, e.g.

the joining of materials to form airtight joints or the mounting ofmechanical elements, are assumed as known, and therefore neitherillustrated nor described.

FIG. 1 shows a conventional. distributor breaker plate 10 which isattached by a pin 11 and rod 12 to a diaphragm 13 in a housing 14.Diaphragm 13 is actuated to retard the setting of the breaker plate 10(thus complementing the setting resulting from other devices, e.g. agovernor) by suction derived from an intake manifold 15 either by acircuit including lead 16, left chamber 17a of a switch assembly 17,lead 18, with vent elements including a lead 19, right chamber 17b andvent 17d, or by an analogous circuit including lead 16, right chamber17b, load 19, with vent elements including lead 18, left chamber 17a andvent 17c, to advance the breaker plate 10.

It is obvious upon inspection of the drawing that the position of theshift piston 20 determines whether the diaphragm 13 will be in theretard position (as shown) or in the advance position (shift piston 20moved to the left). It is further quite apparent that essentially thesame vacuum supply powers the vacuum advance and the vacuum retardposition. Less obvious is the fact that the captive spring 21 and thefree spring 22, in combination, center the diaphragm 13 when there is nosuction in lead 16 or suction insufficient to cause a defiection ineither direction (e.g. when the throttle valve is open or nearly open orwhen the engine is first cranked for starting). This arrangement isparticularly significant in connection with the speedsensitivediscrimination discussed below. The apparent short circuit resultingfrom the provision of a vent in the power circuit (e.g. vent 17c in theillustrated retard circuit) poses no difficulty, as these vents areintended to be much smaller in diameter than the transfering leads (e.g.16 and 18) so that the loss through a vent does not unduly impair thesufficiency of the suction level.

An alternative embodiment of the venting circuits is shown in FIG. 2 inwhich the venting is accomplished in the retard operation by means of ahole and a hole 51, both in rod 23a, a groove 52 and a hole 53 in thehousing 17. When the shift piston 20 is moved to the left-side position,the hole 51 moves away from the groove 52 and the cut 54 previously outof range on rod 23a enters the groove 52, thus providing the vent.

As further shown in FIG. 1, the shift piston 20, with a securelyattached (e.g. bonded) sealing member 20a on its periphery, makes arelatively airtight seal with the cup-shaped walls of the switchassembly housing 17. It is shifted between the right-side extreme(shown) and its corresponding left-side extreme by means of a rodassembly 23 comprising a rod 23a and a rod 23b which are fastened in theshift piston 20, resp. a water diaphragm 24 and connected by means of aconnector 230. On account of the circular form of the shift piston 20,rod 23a may be turned to effect an accurate adjustment of the all-overlength of the rod assembly 23.

The water diaphragm is actuated by the differential in pressure betweenthe water moving in an intake lead 25, which fills its left chamber 24avia a duct 27, and the water following the periphery of a rotor 26a of awater pump 26. Its effectiveness derives from the principle of the pitottube, here shown as the end 28 of a duct 29, whereby the water followingthe periphery of the rotor 26 is caused to rise into the right chamber24b of the diaphragm housing 24c. An arrangement of this type isdescribed in full detail in applicants U.S. Pat. No. 3,204,620 and neednot be elaborated upon here.

Since the water pump is operating whenever the engine is running, eventhough actual circulation may be shut off at times (e.g. by athermostat) so that there is no output in the output duct b, thediaphragm 24 will always be subject to a pressure differential. A spring31 biases the diaphragm 24 for a right-side position, as shown (whichkeeps the shift piston 20 in the position in which the retard circuitdescribed above is operative), and it is so calibrated that it willallow a left-side deflection of the diaphragm 24 only when the pressurein the chamber 24b has reached a predetermined level which maycorrespond to the aforementioned index speed of 1000 rpm. An adjustmentto obtain operation within the speed range of 800-1200 rpm will probablybe desirable. The left-side deflection of the diaphragm 24 will placethe shift piston 20 into its left-side position, and thus activate theadvance circuit, with a hysteresis which may be held negligible byproper design of the interior of switch assembly housing 17, and theparts operating within it to reduce the adverse effect of the engineeffect on the piston 20 and thus activate the advance circuit. It willbe obvious to those skilled in the art that the shift piston 20 could becontrolled with the same effect by any other means, e.g. a fly-ballgovernor, or any means affording a dynamic analog of the engine speed.

The operation of the arrangement according to the invention may bedescribed as follows:

1. During the often recurring short cranking period of a normal start,there will be no suction operated advance or retard; a recognizeddesideratum.

2. During idling (throttle valve 32 in carburetor 30 closed or barelycracked), assuming a normal idling speed of 500-800 rpm, there will be asuction activated retard; another desideratum.

3. In cruising above 1000 rpm, the shift piston 24 will be a suctionoperated advance as long as the manifold suction is strong enough toovercome the resistance of the preloaded spring 31; a third desideratum.

4. At full-throttle or wide-open operation, the manifold suction will beusually too low to overcome the spring 21 and there will then be nosuction operated advance above the predetermined engine speed, andsimilarly no suction operated retard if the shift piston 20 shouldhappen to be in the retard position (lugging), a fourth desideratum.

5. Upon deceleration above 1000 rpm, with closed throttle there will bea vacuum advance; a fifth desideratum.

6. When the engine speed drops through a predetermined speed the suctionoperated advance operation will be shifted to a suction operated retardoperation because the shift piston 20 shifts to the right-side position.This is a sixth recognized desideratum, resulting in reduced exhaustemissions during closedthrottle decelerations and an improvement overheretofore cited prior art, for the reasons stated.

While the invention has been illustrated and described with reference toa preferred embodiment, it will be obvious to those skilled in the artthat it may be adapted to many other embodiments and used, withoutdeparting from the inventive concept. The disclosure herein being thusmerely illustrative, all applications and uses of the invention areclaimed.

I claim:

1. A spark timing control for an internal combustion engine having anintake manifold defining a source of suction comprising a suctionoperated motor connected to a spark timing mechanism, first conduitmeans for connecting said motor to the source and to atmosphere foroperating the motor to produce an advance of the timing of the spark,second conduit means for connection said motor to the source and toatmosphere for operating the motor to produce a retard of the timing ofthe spark, and means responsive to a predetermined speed of engine forselectively connecting the source to said first or second conduit means,the motor comprising a movable wall defining an expansible chamber oneach side thereof, and said first conduit means is connected to onechamber and the second conduit means is connected to the other chamber,said responsive means including a housing having a pair of connect thesource of suction to one of said chambers while closing the source ofsuction to the other chamber and allow said other chamber to bleed toatmosphere.

2. A spark timing control for an internal combustion engine having anintake manifold defining a source of suction comprising a suctionoperated motor connected to a spark timing mechanism, first conduitmeans for connecting said motor to the source and to atmosphere foroperating the motor to produce an advance of the timing of the spark,second conduit means for connecting said motor to the source and toatmosphere for operating the motor to produce a retard of the timing ofthe spark, and means responsive to a predetermined speed of engine forselectively connecting the source to said first or second conduit means,the motor comprising a movable wall defining an expansible chamber oneach side thereof, and said first conduit means is connected to onechamber and the second conduit means is connected to the other chamber,said responsive means including a housing having a valve thereinshiftably mounted between two positions, and said conduit meanscomprises a conduit connecting said housing to said source and separateconduits connecting the housing to each of said chambers, wherebymovement of said valve to one position will connect the source ofsuction to one of said chambers while closing the source of suction tothe other chamber and bleeding said other chamber to atmosphere, theother position will connect the source of vacuum to said other chamberand means bleeding said one chamber.

3. A spark timing control for an internal combustion engine having anintake manifold defining a source of suction and having a throttle valvecomprising, a suction operated motor connected to a spark timingmechanism, first conduit means for connecting said motor to the sourcefor full manifold suction downstream of the idle position of thethrottle valve and to atmosphere for operating the motor by suction toproduce an advance of the timing of the spark, second conduit means forconnecting said motor to the source for full manifold suction downstreamof the idle position of the throttle valve and to atmosphere foroperating the motor by suction to produce a retard of the timing of thespark and means responsive to a predetermined speed of engine forconnecting the source to said first conduit means for producing anadvance of the time of the spark at all positions of the throttle,including closed idle, said responsive means connecting the source tothe second conduit means at a lower than said predetermined speed forproducing a suction operated retard of the timing of the spark.

4. A device as defined in claim 3 wherein the motor comprises a movablewall defining an expansible chamber on each side thereof, and said firstconduit means is connected to one chamber and the second conduit meansis connected to the other chamber.

5. A device as defined in claim 3 wherein the responsive means comprisesvalve means.

6. A device as defined in claim 4 wherein said responsive means includesa housing, a valve therein shiftably mounted between a pair ofpositions, a valve stem connected to the valve for shifting the valve,and bleed conduit means in said stem for selectively bleeding one of thechambers to atmosphere while the other chamber is connected to thesource of vacuum as the valve is shifted to one or the other of saidpositions.

7. A device as defined in claim 4 wherein said responsive means includesa housing, a valve therein shiftably mounted between a pair ofpositions, for alternately connecting each of the chambers to the sourcewhile bleeding the other to atmosphere.

1. A spark timing control for an internal combustion engine having anintake manifold defining a source of suction comprising a suctionoperated motor connected to a spark timing mechanism, first conduitmeans for connecting said motor to the source and to atmosphere foroperating the motor to produce an advance of the timing of the spark,second conduit means for connection said motor to the source and toatmosphere for operating the motor to produce a retard of the timing ofthe spark, and means responsive to a predetermined speed of engine forselectively connecting the source to said first or second conduit means,the motor comprising a movable wall defining an expansible chamber oneach side thereof, and said first conduit means is connected to onechamber and the second conduit means is connected to the other chamber,said responsive means including a housing having a pair of bleedopenings connected to atmosphere and a valve therein shiftably mountedbetween a pair of positions and said conduit means comprises a conduitconnecting said housing to said source and separate conduits connectingthe housing to each of said chambers whereby movement of the valve toone position will connect the source of suction to one of said chamberswhile closing the source of suction to the other chamber and allow saidother chamber to bleed to atmosphere.
 2. A spark timing control for aninternal combustion engine having an intake manifold defining a sourceof suction comprising a suction operated motor connected to a sparktiming mechanism, first conduit means for connecting said motor to thesource and to atmosphere for operating the motor to produce an advanceof the timing of the spark, second conduit means for connecting saidmotor to the source and to atmosphere for operating the motor to producea retard of the timing of the spark, and means responsive to apredetermined speed of engine for selectively connecting thE source tosaid first or second conduit means, the motor comprising a movable walldefining an expansible chamber on each side thereof, and said firstconduit means is connected to one chamber and the second conduit meansis connected to the other chamber, said responsive means including ahousing having a valve therein shiftably mounted between two positions,and said conduit means comprises a conduit connecting said housing tosaid source and separate conduits connecting the housing to each of saidchambers, whereby movement of said valve to one position will connectthe source of suction to one of said chambers while closing the sourceof suction to the other chamber and bleeding said other chamber toatmosphere, the other position will connect the source of vacuum to saidother chamber and means bleeding said one chamber.
 3. A spark timingcontrol for an internal combustion engine having an intake manifolddefining a source of suction and having a throttle valve comprising, asuction operated motor connected to a spark timing mechanism, firstconduit means for connecting said motor to the source for full manifoldsuction downstream of the idle position of the throttle valve and toatmosphere for operating the motor by suction to produce an advance ofthe timing of the spark, second conduit means for connecting said motorto the source for full manifold suction downstream of the idle positionof the throttle valve and to atmosphere for operating the motor bysuction to produce a retard of the timing of the spark and meansresponsive to a predetermined speed of engine for connecting the sourceto said first conduit means for producing an advance of the time of thespark at all positions of the throttle, including closed idle, saidresponsive means connecting the source to the second conduit means at alower than said predetermined speed for producing a suction operatedretard of the timing of the spark.
 4. A device as defined in claim 3wherein the motor comprises a movable wall defining an expansiblechamber on each side thereof, and said first conduit means is connectedto one chamber and the second conduit means is connected to the otherchamber.
 5. A device as defined in claim 3 wherein the responsive meanscomprises valve means.
 6. A device as defined in claim 4 wherein saidresponsive means includes a housing, a valve therein shiftably mountedbetween a pair of positions, a valve stem connected to the valve forshifting the valve, and bleed conduit means in said stem for selectivelybleeding one of the chambers to atmosphere while the other chamber isconnected to the source of vacuum as the valve is shifted to one or theother of said positions.
 7. A device as defined in claim 4 wherein saidresponsive means includes a housing, a valve therein shiftably mountedbetween a pair of positions, for alternately connecting each of thechambers to the source while bleeding the other to atmosphere.